The present invention relates to a method and apparatus for regulating the mixture or fuel quantity fed to the cylinders of an internal combustion engine using an arrangement for the variable metering of the mixture or fuel quantity to the cylinders of the internal combustion engine, a device for acquiring the actual value of the mixture or fuel quantity to be fed in, by means of measuring the stroke of a valve means that are arrange movably in the metering arrangement, and an arrangement for regulating the valve movement.
German Patent Document 3,831,663 discloses a fuel injection system for internal combustion engines in which the actual value of the fuel supply to the cylinders of the internal combustion engine is acquired via a measurement of the stroke movement of a valve means in a metering arrangement. The fuel quantity to be fed in is determined in a control unit as a function of engine parameters, taking into account the actual value, and is transmitted to the metering arrangement as an actuating signal.
Particularly in the idling mode of an internal combustion engine, i.e. at low loads and speeds, differences between individual cylinders as regards their filling or injection quantity are clearly perceptible. In order to compensate for these differences by an individual regulation, very high requirements are set for the accuracy of this regulation. The acquisition of the stroke or of the stroke characteristic of the valve means for actual value determination is, in particular, very expensive and yet cannot be accomplished with sufficient precision in production engines.
An object of the present invention is to improve a regulation facility of the above-described type for mixture or fuel-quantity metering in such a way that the actual value of the metered quantity can be determined with great accuracy where simple and cheap sensors are used.
This and other objects are achieved by the present invention which provides a method for regulating the mixture or fuel quantity fed to cylinders of an internal combustion engine that has an arrangement for the variable metering of the mixture or fuel quantity to the cylinders of the internal combustion engine, means of measuring a stroke of valve means that are arranged movably in the metering arrangement, and an arrangement for regulating the valve movement. The method of the present invention includes the steps of: measuring of a stroke of the valve means allocated to each cylinder to acquire an actual value of the mixture or fuel quantity fed in; determining a stroke duration of the valve means allocated to each cylinder; and regulating the stroke duration to an identical value for all valve means.
The objects of the invention are also achieved by a device constructed in accordance with an embodiment of the present invention which provides a device for regulating the mixture or fuel quantity fed to cylinders of an internal combustion engine. The device includes a metering arrangement for the variable metering of the mixture or fuel quantity to the cylinders of the internal combustion engine, valve means arranged movably in the metering arrangement, means for measuring a stroke of the valve means allocated to each cylinder to acquire an actual value of the mixture or fuel quantity fed in, an arrangement for regulating the movement of the valve means, means for determining a stroke duration of the valve means allocated to each cylinder, and means for regulating the stroke duration to an identical value for all valve means. The means for measuring a stroke of the valve means includes a position sensor for each valve means, this position sensor providing as an output to the means for determining a stroke duration a signal when a stroke of the valve means is overshot or undershot.
To acquire the actual value of the mixture quantity (in the case of mixture-compressing internal combustion engines) or of the fuel quantity (in the case of air-compressing internal combustion engines) fed to each cylinder, the duration of the stroke of the valve means provided in the metering arrangement is measured. For this purpose, the overshooting of a particular stroke threshold value of the valve means is detected by means of a position sensor. The duration between the overshooting of this threshold value and the subsequent undershooting of the threshold value upon closure of the valve means, i.e., the stroke duration, is a measure of the actual value of the mixture or fuel quantity fed in. This actual value is acquired for all the cylinders of the internal combustion engine and, to compensate for differences in the filling or injection quantity of each cylinder, is regulated by corresponding actuation of the valve means to an identical value for all the cylinders of the internal combustion engine.